In the medical arts, sharp pointed needles are used for a variety of procedures. Devices having sharp pointed needles are used for example, in administering fluids to patients either directly or in through intravenous apparatus. In addition, needles are used in various blood drawing applications either with syringes or specialized holders for filing collection tubes.
The medical profession recognizes exposure to blood borne pathogens as a potential hazard. As a result of this recognition, numerous protocols for use of needles have been developed and are widely practiced. The problem of transmission of blood borne pathogens not only exists for the physician, nurse or phlebotomist using the needles but also for the support staff throughout the hospital. Since most needles in use today are single-use and disposable, hospital service personnel like housekeeping, laundry and maintenance are at risk from needles that are not properly handled by the users.
The use protocols generally dictate in detail when and how a needle is used and how it should be disposed. The problem with many protocols for handling needles is that the protocols often require users to perform additional steps in the procedure. Certain practices regarding handling of used needles are sometimes disregarded and injuries still occur. The medical device industry has responded to the problem by producing a wide variety of needle shielding devices and retractable needle syringes to assist practitioners in their need to reduce the occurrence of needle injuries.
There has been increased emphasis in designing hypodermic syringes with extendible shields which protect and project over the needle area after injections are completed. Although these devices are well suited to reduce the occurrence of needle injuries, some such devices can be cumbersome and difficult to dispose.
A growing area in the medical device industry to limit the exposure of blood borne pathogens is in the area of retractable needle syringes. Retractable needle syringes generally allow the needle to retract within the syringe after the syringe has been used. The syringe usually includes a hollow plunger which is inserted into one end of the syringe barrel. The syringe usually includes a spring or some other resilient means to push the used needle into the hollow plunger rod. Other retractable needle syringes use a means to pull the used syringe and hub into the syringe barrel where the plunger rod is then broken off to discourage re-use of the syringe. In both of these configurations of retractable needle syringes, the plunger rod usually activates the mechanism to retract the needle or the needle hub. These designs allow retraction of the needle while the plunger rod is forced in the same direction as the injection. The purpose of that design function is reportedly to allow the user a one-handed technique to retract the needle in the syringe thereby avoiding exposure to the sharp end of the needle.
However, these designs have a tendency to prematurely activate as the user is injecting the medication with the syringe. Also, these devices can prematurely activate during manufacture of the syringes when the plunger rod is inserted into the back end of the syringe barrel.
There remains a need for an improved design of a syringe in which the plunger rod does not prematurely activate the retracting means to retract the needle within the syringe. There is also a need to prevent reuse of the syringe and allow safe and easy disposal.